1. Field of the Invention
The present invention relates generally to the art of electroless deposition and particularly to the direct deposition of cuprous oxide. The present invention also relates specifically to multiple-glazed units with a cuprous oxide coating on at least one surface.
2. Description of the Prior Art
Transparent articles bearing transparent metal films have been produced by well-known electroless coating techniques which involve contacting a surface to be coated with a metal salt and a reducing agent to deposit a metal film onto the surface by chemical reduction.
Autocatalytic techniques wherein a metal salt and a reducing agent are present in a single solution and react upon contact with a catalytic surface are described in U.S. Pat. Nos. 2,532,283 and 2,532,284 for the deposition of cobalt and U.S. Pat. No. 2,956,900 for the deposition of nickel. Exhaustive techniques wherein the metal salt and reducing agent react rapidly and so are applied to the surface to be coated in separate solutions are described in U.S. Pat. No. 3,671,291.
Such electroless coating techniques have been successfully employed for the direct deposition of thin transparent metallic films of iron, cobalt, nickel, copper, silver and mixtures thereof on nonmetallic substrates such as sheets of glass. The films so produced have suitable transmittance, reflectance and uniform thickness to provide coated articles with important solar energy control characteristics and a uniform aesthetic appearance.
Electrolessly deposited metal films may be oxidized in order to obtain optical and spectral properties which differ from the properties of the initially deposited metals. In U.S. Pat. No. 3,846,152, articles for the selective reflectance and transmittance of radiation over an extended spectral range are disclosed. Such articles are produced by coating a substrate with a first film of silver, iron, cobalt, chromium or nickel; coating with a second metal film of copper or iron; and oxidizing the second metal film by heating.
In U.S. Pat. No. 3,920,864 a method is disclosed for treating a copper-coated article with a solution which effects partial replacement of copper by silver. The copper-silver composite film is subsequently oxidized by exposure to moist air.
As an alternative to the subsequent oxidation of electrolessly deposited metal films, a method is disclosed in U.S. Pat. No. 3,978,272 for the direct deposition of metal oxide films. Such films are deposited by spraying a solution of a metal compound onto the substrate which is sufficiently hot to thermally decompose the metal compound thus forming a metal oxide film by pyrolysis.
In U.S. Pat. No. 3,694,299, a method is described, wherein an organometallic film forming material is deposited on a surface of a glass sheet which is assembled with another glass sheet to form a multiple glazed unit and is heated to form a metal oxide film on the interfacial surface of the glass sheet prior to fusing the edges of the glass sheets to form a welded multiple glazed unit.